Thomas enters the 2019 Tour as defending champion after his victory last year but there are doubts about his Grand Tour form after he crashed out of the recent Tour de Suisse. The 22-year-old Bernal missed the Giro d'Italia after a crash in training but recovered quickly and went on to win the Tour de Suisse, earning his role as joint leader.
Team Ineos will be without four-time winner Chris Froome after his high-speed crash at the Critérium du Dauphiné but are still expected to dominate the racing, with Thomas and Bernal potential winners.
The racing and the roads of France will ultimately reveal who will emerge as Team Ineos' protected leader, with the first mountain finish to La Planche des Belle Filles likely to give a first indication who is climbing better.
"It's no secret my build-up has been affected by the crash at Tour de Suisse, but I've had a good block of training since and I feel ready. Discussing with the team, we believe it makes sense to go into the race with joint leaders as it gives us more options. Egan and I will work hard for each other and the team over the three weeks of the race," Thomas said when the Team Ineos line-up and shared leadership strategy was revealed on Friday.
"Winning the Tour de France last year was the highlight of my professional cycling career and racing with the number one on my back is going to be special this year. The memories of 2018 will remain with me forever, but now I'm ready to create more with the team this year.
"We've got a really exciting blend of youth and experience in the team – and it's a group of riders who I know will be with me every step of the way and know what it takes to win Grand Tours. I can't wait to pull on the Team Ineos jersey for the first time at the Tour de France in what is the biggest race of the year."
Thomas will ride the tenth Tour de France of his career, while Bernal is about to start his second.
"I have really good memories from the Tour last year," Bernal said. "It was my first Tour de France and also my first Grand Tour, so it was special. We enjoyed a great victory with G and it was something really special to be a part of. Of course, our ambition is to win the race again this year.
"Last year's experience taught me a lot. As a bike rider, whatever you might think about the Tour from the outside you don't really know it until you have raced it. Now I know what to expect, I can be more relaxed about what lies ahead and even more focused on the racing. The most important thing for my development is to enjoy racing over the next three weeks, give my best, and be happy with my performance. I am looking forward to sharing leadership responsibilities with G and doing everything we can together to help Team Ineos win its first Tour."
Five return from 2018 squad
The eight-rider line-up also includes Jonathan Castroviejo, Michal Kwiatkowski, Gianni Moscon, Wout Poels, Luke Rowe and Dylan van Baarle, giving the team strength for the stage 2 team time trial, the dangerous flatter stages and the decisive mountains. Castroviejo, Kwiatkowski, Moscon, Poels and Rowe all helped Thomas to win in 2018.
Moscon was expelled from last year's race after aiming a blow at Elie Gesbert in the opening kilometres of stage 15. The Italian was later handed a five-week ban by the UCI.
This year's Tour will feature 30 categorised climbs, five mountain-top finishes and only 54 kilometres of time trialling, split between the team time trial and one individual time trial on stage 13. It will be the first time the British WorldTour outfit targets the Tour de France as Team Ineos after the multinational petrochemicals brand took over ownership and title sponsorship from Sky.
"There is always a strong sense of anticipation before any Tour, but this one is that bit more special for us as it's our first racing as Team Ineos. And whilst our preparation hasn't been straightforward following Chris Froome's recent crash, we will be at the start line with a really strong team that is hungry to win again," team manager Dave Brailsford said.
"After the success of last year, we have decided to come into the race with joint leaders. Geraint and Egan are both in great form. They trust each other and we believe that this approach will best suit us as a team by giving us the greatest flexibility on the road and the best possible chance of success.
"Alongside them, we have five of the riders who supported Geraint in his victory last year. They are all supremely talented in their own right as bike riders and also in great form, but their combined strengths will ensure we are strong on both the flat and in the mountains. We have also brought Dylan van Baarle into the team. He was in top condition at the Dauphine and is relishing the opportunity ahead."
The Tour de France gets underway in Brussels on July 6.
Team Ineos for the Tour de France: Egan Bernal (Col), Geraint Thomas (GBr), Jonathan Castroviejo (Spa), Michal Kwiatkowski (Pol), Gianni Moscon (Ita), Wout Poels (Ned), Luke Rowe (GBr) and Dylan van Baarle (Ned).